All the utilities here are run by single providers. There is no choice in the market and service etc generally reflects this! Some leases will leave the utilities in the name of the landlord and you will be billed by them in arrears. This can be simpler but could come with its own frustrations if there are any problems.
There is basically not enough electricity to go round all the people and businesses in South Africa. As a result power outages are not uncommon. There is often much talk of load shedding in the winter months when people are using their heating, though for the last few years this hasn’t been happening as much.
The electricity company is called Eskom. For Johannesburg users you’ll encounter them as “City Power”. Electricity prices are high and tariffs seem to be going up endlessly! There is also pay as you go electricity available.
There is very very limited residential gas here. Most homes with any gas use bottled gas suppliers who will deliver to your door. It may be a good idea to have gas cooking facilities since power outages can leave you with no way to cook otherwise!! A lot of South Africans use the good old fashioned gas heaters in the winter!
Water is provided by Johannesburg water. It is reasonably good quality and drinking tap water is safe and widely done!